We derive the Cramér-Rao lower bound (CRLB) on the covariance of the joint estimates of the parameters of moving targets using measurements from multiple-input, multiple-output (MIMO) radars. We first derive the CRLB for MIMO radars with colocated antennas for estimating the target's direction of arrival, range and range-rate. We then demonstrate that the CRLB for phased array radars is a special case of the CRLB for MIMO radars with colocated antennas. We also derive the CRLB for MIMO radars with widely-separated antennas for estimating the target's location and velocity, and we compare it to the CRLB for the multistatic radar. For both types of MIMO radar systems, we show that the CRLB is related to the parameters of the transmitted waveforms, as demonstrated with numerical simulations.